Abit Video Card Install With Error Message, Please Help!

Hi. A While ago my Abit Radeon RX 600 XT Graphics Card began making a noise coming from the fan. After start up it would not spin and make a moaning sound until after a few minutes, it would then spin freely. I contacted the Abit parts center and was sent a replacement chipset fan which I plugged into the factory location. The fan and everything works great after start up and while using the computer. But when I go to shut it down the screen says” Windows is shutting down" but then a blue screen comes on and says "NMI Parity/Memory Error. This system has halted. Contact Your Hardware Vendor for Suport." The computer stays on this blue screen and will not shut off and I cannot make the message go away unless I hold in the reset switch for 5 seconds. I have never had this problem/message until I installed the replacement fan into the card, and I even reinstalled it making sure it was properly seated. What could this be? Please help, this error message is becoming very annoying. I have a Dell Dimension 8400 Pentium 4 3.0Ghz. At first after installing the replacement fan the computer would shut down normally (every other shut down). But as time progressed, it would never shut down without giving me this error message and having to hold in the reset button.
Thank You
Brian.